Webbing is commonly attached to a furniture frame member by hand. The webbing is typically attached to one side of a wooden frame by staples. The user then stretches the webbing across the frame and staples it to the other side of the wooden frame. This step is repeated for the desired number of pieces of webbing to be attached to the wooden frame. This process is slow and time consuming. Further, the process does not provide consistent tension of the webbings across the frame. Still further, the process does not provide consistent spacing between the webbings without hand measurement.
Sometimes steel frames are used in seating applications with elastomeric webbing for strength and durability purposes. In certain applications, such as the contract and medical seating industries, a seating structure must be durable enough to pass stringent cycle and drop tests, such as the ANSI/BIFMA X5.1 Office Chair Test or the ANSI/BIFMA X5.4 Lounge and Public Seating Test. For purposes of passing these tests, traditional methods of attaching a strap of webbing to a steel frame have proven to be a weakness in terms of cost and/or durability.
One type of known method of attaching webbing to steel frames is to sew the webbing into a large loop, which would then be stretched over the width or depth of the steel frame. This method requires twice the length of webbing as other methods, which can make it cost-prohibitive.
A more common method has been to attach a strip of webbing to a wire hook, which is then engaged in a hole in the steel frame. The webbing can be sewn to itself around the wire hook or clamped by a sleeve or collar. Most of these wire hooks are shaped like a coat hanger, comprising a flat section passing through the end loop of the webbing, with the two ends bending around the end of the webbing, coming back together in the center to form a triangular shape, then bending back together to form a hook to engage a single hole in the metal frame. This type of attachment hook has created problems in testing. One such problem is when the webbing is only attached to the wire hook by a clamping collar, the impact loads of the cycle or drop test can cause the webbing to slip through the collar, causing a significant or complete loss of support from the webbing. Another problem is when the webbing is secured to the wire hook via a sewn seam, without the clamping collar, then the flat part of the hook can deform under the impact loads of the cycle or drop test, causing a loss of support due to the change in the effective elongation of the webbing. Another problem is when the webbing or strap is sewn to itself around the flat section of the wire hook and the clamping collar is added, the flat section of the wire hook is reinforced, so the slippage and bending problems may be reduced. However, the wire hooks are still prone to breakage during cycle testing, typically in the bends where the wire emerges from the end loop of the webbing.
Consequently, there is a need for a wire hook for use with webbing for seating products which may be used in the end loops of the webbing and requires less wire than known wire hooks.
Further, there is a need for a wire hook for use with webbing for seating products which eliminates movement of the wire hooks in the holes and therefore, eliminates noise and wear.